The morning news. [volume] (Savannah, Ga.) 1887-1900, 1887-09-19
CYCLONES AND roRNADoEs.
The Difference Between the Two
Great Atmospheric Terrors.
From the Chicago Inter Ocean.

Great atmospheric Terrors.
From the Chicago Ilter- Ocean.
In common speech no difference is recog-
nized between these two classes of storms,
but accurately speaking they are essentially
different. The cyclone is an ocean storm,
it has its origin in the tropical seas of both
hemispheres and moves toward the north.
The entire body OF wind. or storm, has for
cyclones of the western hems-
phere originate in the West Indies,
travel northwest until they reach arout
30 latitude north, then curve to the north
east and continue in that directlon-some.
times at some distance of the coast and some
times on the shore, finally trending ocean
ward and disappearing in the vicinity or
80 latitude north. The diameter of the
storm varies from several hundred to over
Zoo miles, and its velocity is from sixty TO
eighty miles an hour. At no point does the
air whirl in a circle, but there is tendency
OF the entire body Of the storm TO revolve
around the point of lowest barometer. As
a rule the velocity of the wind increases
gradually till it eliminates in fierce in
tensity of movement that will wreck the
largest ships In the actual centre of the
storm there is a dead calm.
Cyclones occur most frequently between
August and November. In the eastern
hemisphere they form in the vicinity of the
Philippine Islands, moving thence north
westward to the Asatic coast, and then
curving to the northeast over the adjacent
seas and islands They are there known as
typhoons The origin in both hemispheres
can be placed at about ten to
twelve degrees north of the equa-
tor, between the belt of Gains and
the southern limit of the trade winds.
The tornado, on the other hand, is always
a mi or &c Ne al Prov,
southwest to northeast, and its path varies
from few yards to eighty rods in width.
The moving air always makes its appear
ance in the form Of funnel-shaped cloud,
the small end drawing near to the earth,
and reyolves about a central, vertical axis
with inconceivable rapidity, and always in
right to left direction. or opposite to the
movement of the hands of watch With
scarce an exception the tornado occurs in
the afternoon, just when the hottest part of
the day is over 1t is caused by heat, that
is, by the contact of currents of low tenn
perature from the north with those of ex-
tremely high temperature from the south.
The struggle of these atmospheric forces
toward an equilibrium of temperature pro-
duces the mass Of swiftly whirling air which
we know as the tornado cloud The veloc-
ity of the particles of air in this mass is so
great that it is difficult SO estimate it, but it
is believed to be from 100 to 500 miles an
hour, and is sometimes, no doubt, even
greater than this
Observers note four motions of the tor
nado cloud. /, the gyratory movement of
its air particles: 2, the onward motion of the
storm; 3, the rising and falling movement
of the cloud, and 4, its oscillation or sway
ing from side to side. 1t is also stated that
the force of the tornado is constant, that it
does not seem to spend itself, as the phrase
is, by the destruction of the strongest build
.,,a- e
the earth upward, evidently being acted
upon by forces in the upper region of the
atmosphere.
Close observation such as has been made
of many tornadOes under the direction of
the Signal Service, seems to show that
electricity is not an active cause of the tor
nado, but is often present as an accompani-
rapid motion of the air. Hail al
ways accompanies a tornado, being
formed by the same cause, that
is the rapid condensation of the moisture of
southern winds by contact with cold north
ern currents Lightning and thunder never
attend on the tornado cloud itself, but some
times appear in the region of other outside
clouds, while the tornado cloud is in mo-
ton.
To conclude. we quote from the recently
published work of Lieut. Finley, of the Sig
nal Service or ''Tornadoesr-to which we
are indebted for the facts summarized above
the following description of the forma-
tion of tornado cloud: 1.-TWO currents of
air approaching each other from opposite
points will not come directly together, be-
cause of the influence of the relative motion
of the earth The mass of air coming from
the South would have a greater We
locity eastward than that coming
from the North. Therefore, instead
of meeting each other in direct
line, the two currents will form an angle at
their intersection and the combination of
the two masses win give rise to rotation
in direction contrary to the hands of a
watch with its face upward. These condi-
tions account for the spiral movement of the
air currents and the formation of the vor-
tex in the tornado. The cold air from the
northward will under-run the warmer air
from the southwark, because of the differ
ence in the density of the two masses, and
as a result will aid in the formation of the
Whirl